Without limiting the scope of the present invention, its background will be described with reference to producing fluid from a subterranean formation, as an example.
After drilling each of the sections of a subterranean wellbore, individual lengths of relatively large diameter metal tubulars are typically secured together to form a casing string that is positioned within each section of the wellbore. This casing string is used to increase the integrity of the wellbore by preventing the wall of the hole from caving in. In addition, the casing string prevents movement of fluids from one formation to another formation. Conventionally, each section of the casing string is cemented within the wellbore before the next section of the wellbore is drilled.
Once this well construction process is finished, the completion process may begin. The completion process comprises numerous steps including creating hydraulic openings or perforations through the production casing string, the cement and a short distance into the desired formation or formations so that production fluids may enter the interior of the wellbore. The completion process may also include installing a production tubing string within the well casing which is used to produce the well by providing the conduit for formation fluids to travel from the formation depth to the surface.
To selectively permit and prevent fluid flow into the production tubing string, it is common practice to install one or more sliding sleeve type flow control devices within the tubing string. Typical sliding sleeve type flow control devices comprise a generally tubular body portion having side wall inlet openings formed therein and a tubular flow control sleeve coaxially and slidably disposed within the body portion. The sleeve is operable for axial movement relative to the body portion between a closed position, in which the sleeve blocks the body inlet ports, and an open position, in which the sleeve uncovers the ports to permit fluid to flow inwardly therethrough into the interior of the body and thus into the interior of the production tubing string. The sliding sleeves thus function as movable valve elements operable to selectively permit and prevent fluid inflow. Generally, cylindrical shifter tools, coaxially lowered into the interior of the tubing string, are utilized to shift selected ones of the sliding sleeves from their closed positions to their open positions, or vice versa, to provide subsurface flow control in the well.
It has been found, however, that typical sliding sleeve type flow control devices are not suitable in completions requiring sand control as they are not compatible with typical sand control screens. Recently, a device has been proposed that combines sand control and fluid flow control, which was disclosed in U.S. Pat. No. 5,896,928. Specifically, the device includes a generally tubular body for placement into the wellbore. The tubular body has a sand control screen at an outer surface for preventing sand from entering into tubular body. After the fluid flows through the sand control screen it must pass through a labyrinth. A slidable sleeve on the labyrinth controls the fluid velocity therethrough. The slidable sleeve is moved by a remotely and electrically-operated device placed in the tubular body. The fluid leaving the labyrinth passes to the tubing string for carrying the fluid to the surface.
It has been found, however, the labyrinth type flow control devices are difficult and expensive to manufacture and can be unreliable under certain inflow conditions. Accordingly, need has arisen for a fluid flow control device for controlling the inflow of formation fluids in a completion requiring sand control. A need has also arisen for such a fluid flow control device that is not difficult or expensive to manufacture. Further, a need has arisen for such a fluid flow control device that is reliable in a variety of flow conditions.